Why this matters
Avoids worsening already-unstable services and reduces incident risk from incremental latency.
If a PR changes an API endpoint/controller/route, assess current production health before adding heavier logic. - If a monitoring MCP is available (Datadog/Grafana): query current p95 latency and error rate for that endpoint. - If the endpoint is already degraded, warn against adding heavy queries, blocking I/O, or complex synchronous logic; require performance evidence or a safe rollout plan. To enable this check, the PR should reference the endpoint path (e.g., `POST /api/payments`) or the controller/action name.
Avoids worsening already-unstable services and reduces incident risk from incremental latency.
Side-by-side examples engineers can pattern-match during review.
Adds multiple DB queries inside a hot endpoint with no monitoring/rollout plan.Checks endpoint health, adds caching/index, benchmarks, and rolls out behind a flag.Changed controller; no endpoint reference; no perf signalMentions route + includes p95/error snapshot + mitigationFrom the same buckets as this rule.
All static JS/CSS/font/image files MUST use content-hashed filenames (e.g., app.9c1a7b.js) and be served with "Cache-Control: public, max-age=31536000, immutable". HTML and other non-fingerprinted documents MUST be served with "Cache-Control: no-cache" (or equivalent) to enable conditional revalidation.